Electrolytic diazo process



Feb. 13, 1951 w. VANSELOW ET AL 2,541,488

ELECTROLYTIC DIAZO PROCESS Filed March 14, 1946 CA THODE v D 42 1 C SUPP! Y APER ANODf/ DYE FORMING MATERIALS IN OR ON UPPER SURFACE OF PAPER WALDEM U? VANSELOW HENRY C .YUTZY INVENTORS W (2. adj

A TTORNE YS Patented Feb. 13, 1951 ELECTROLYTIC DIAZO PROCESS Waldemar Vanselow and Henry C. Yutzy, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application March 14, 1946, Serial No. 654,442

This invention relates to diazo photographic processes and particularly to a process in which the image is produced electrochemically.

Diazotype materialshaving a carrier of gelatin, regenerated cellulose, cellulose derivative or paper, containing a diazonium compound and a coupler are well known in the photographic art. Such materials generally contain an acid or similarly effective agents to prevent premature coupling and after exposure the coupling is brought about by treatment with ammonia gas or other alkaline medium. In electrolytic treatment of diazo material, there is no exposure to light but the alkalization is brought about by passing a current through the paper from a stylus, the pH being thereby raised locally .to permit coupling.

We have found that an image may be formed in a diazotype material after exposure to light by passing a direct current uniformly through the material to raise the pH over the entire region of exposure, thereby producing a visible image.

The accompanying drawing shows diagrammatically the method of forming an image in the diazotype material according to our invention.

According to our invention a support material such as a rather absorbent paper is coated with a diazonium compound, a coupler, an acid stabilizer and an electrolyte to assure passage of the current through the material. The material is then dried and exposed in the customary manner to an image. Generally a positive image is used for the exposure and positive image is then produced in the diazo material.

The paper or other exposed material is moistened slightly after exposure and then placed between two flat electrodes. direct current between the electrodes and through the exposed diazo material a positive image is produced in the material.

In the accompanying drawing this method of forming an image in the diazo material is diagrammatically represented. As shown therein the exposed diazo material B is placed between the flat electrodes A and C with the side on which the image is to be formed, uppermost or adjacent the cathode C. A direct current is then passed from a supply source, not shown, through the electrodes, the positive terminal being connected to plate A and the negative terminal to plate C. Upon passage of a. current of the proper potential for a sufi'icient length of time a visible image is produced in the diazo material.

Our invention will now be illustrated by reference to the following example:

Upon passage of a I 2 Claims. (Cl. -6)

An absorbent paper was bathed in a 5 to 10% solution of sodium chloride and was partially or completely dried. One surface was then coated with a solution of the following composition:

Diazonium compound of N (p aminophenyl) morpholine grams 1 ,B-Naphthol do 1 Hydrochloric acid cc 1 Boric acid grams 1 Tartaric acid l do 2 Thiourea do 0.1 Ethyl alcohol cc 50 Water cc 50 The paper was then dried and exposed in the customary manner behind a positive. After exposure the paper was moistened slightly with an atomizer and placed between two flat electrodes. The cathode was a silver plate approximately 9 square centimeters in area and the anode was a graphite plate of similar area. A D. 0. potential of 22 volts was applied to the electrodes, the current being 1 to 4 amperes depending upon the moisture content of the paper. The current was passed for 0.2 to 2.0 seconds and after this time a dark reddish brown print on a pale tan field was produced.

Variations in this method include introducing the salt into the diazo mixture instead of incorporating it in the paper support, the use of a hygroscopic material such as glycerin'in the paper to insure adequate moisture content, and the use of electrode rollers so that the process may be made continuous. Stainless steel electrodes may be used. The electrolyte must be in the support, rather than merely on the surface so that the material is conductive when the current is passed through it.

The electrolyte may comprise any suitable water-soluble inorganic acid salt such as sodium chloride, magnesium chloride, sodium nitrate or sodium sulphate. If a halide such as a chloride is used as the electrolyte, proper precautions must be'taken to remove the corrosive halogen which is liberated at the anode.

While we have illustrated our invention as using the diazonium compoundof N-(p-aminophenyl) -morpho1ine, fi-naphthol as the coupler, other aromatic diazonium salts and aromatic hydroxy coupling compounds may be employed. For example, suitable diazo salts include the diazo salts of N-p-aminophenyl morpholine, N- p-amino-m-tolyl morpholine, N-p-aminophenyl piperidine, N-(3-methyl-4-aminophenyl) piperidine, N-p-aminom-anisylmorpholine, N-p-amino-o-chlorophenyl morpholine, the corresponding naphthalene derivatives of these compounds, 1-amino-4-dimethyl-aminobenzene, p-amino-dimethylaniline, 4 amino 1-monoethylamino-2- toluene, l-benzoylamino 2,5-diethoxy-4-ani1ine, l-amino 4 hydroxybenzene, 4-amino-l-cyclohexylaniline, the tetrazo salt of. diaminodiphenyl thiourea, 1-amino-2-hydroXy-3-naphthoic acid, 1,2,4-aminonaphthol-sulfonic acid and similar diazo sensitizing compounds. Instead of B-naphthol, couplers such as phloroglucionol, resorcinol, dichloro-resorcinol, a-naphthol, 2,4-dichloro-1- naphthol, H-acid, R-acid and: the like may be used. The acid stabilizer may be an organic or inorganic acid such as hydrochloric acid, boric acid, tartaric acid. Thiourea may also be used.

The modifications and examples included herein are illustrative only and it will be understood that our invention is to be taken as limited only by the scope of the appended claims.

We claim:

1. The method of forming an image electrolytically by the diazo process, which comprises incorporating a water-soluble inorganic acid salt electrolyte in an absorbent sheet material support, adding to said support an aromatic diazonium salt, an aromatic hydroxy coupling compound, and an acid stabilizer, exposing. said support to light under an image, moistening said support before passage of said after-mentioned current, placing the side of said support having said diazonium salt, coupling compound and stabilizer adjacent and in contact with the cathode plate of a direct current source, and placing the anode plate of said direct current source adjacent and in contact with the opposite side of said support, and passing a direct current uniformly through the entire area of said support to form a visible image in the unexposed regions thereof.

2. The method of forming an image electro lytically by the diazo process which comprises incorporating sodium chloride as an electrolyte in an absorbent paper support, adding to said support the diazonium salt of N-(p-aminophenyl) morpholine, p-naphthol, and an acid stabilizer, exposing said support to light under an image, moistenin-g said support before passage of said after-mentioned current, placing the side of said support having said diazonium salt, coupling. compound and stabilizer adjacent and in contact with the cathode plate of a direct current source and placing the anode plate of said direct current source adjacent and in contact with the opposite side of said support, and passing a direct current uniformly through the entire area of said support to form a visible image in the unexposed regions thereof.

WALDEMAR VANSELOW. HENRY C. YUTZY.

REFERENCES CITED The following references are of record in the file. of this patent:

UNITED STATES PATENTS.

Number Name Date 1,444,469 Kogel Feb. 6, 1923 1,892,099 Cornell Dec. 2'7, 1932 1,970,539 Bausch Aug. 21, 1934 2,306,471 Solomon Dec. 29, 1942 2,433,632 Solomon Dec. 30, 1947 FOREIGN PATENTS Number Country Date 317,444 Germany Dec. 16, 1919 358,584 Germany Sept. 12, 1922 464,112 Great Britain Apr. 12, 1937 

1. THE METHOD OF FORMING AN IMAGE ELECTROLYTICALLY BY THE DIAZO PROCESS, WHICH COMPRISES INCORPORATING A WATER-SOLUBLE INORGANIC ACID SALT ELECTROLYTE IN AN ABSORBENT SHEET MATERIAL SUPPORT, ADDING TO SAID SUPPORT AN AROMATIC DIAZONIUM SALT, AND AROMATIC HYDROXY COUPLING COMPOUND, AND AN ACID STABILIZER, EXPOSING SAID SUPPORT TO LIGHT UNDER AN IMAGE, MOISTENING SAID SUPPORT BEFORE PASSAGE OF SAID AFTER-MENTIONED CURRENT, PLACING THE SIDE OF SAID SUPPORT HAVING SAID DIAZONIUM SALT, COUPLING COMPOUND AND STABILIZER ADJACENT AND IN CONTACT WITH THE CATHODE PLATE OF A DIRECT CURRENT SOURCE, AND PLACING THE ANODE PLATE OF SAID DIRECT CURRENT SOURCE ADJACENT AND IN CONTACT WITH THE OPPOSITE SIDE OF SAID SUPPORT, AND PASSING A DIRECT CURRENT UNIFORMLY THROUGH THE ENTIRE AREA OF SAID SUPPORT TO FOAM A VISIBLE IMAGE IN THE UNEXPOSED REGIONS THEREOF. 